Happy_AltRight I think popularity depends not only on the quality of the novel but also on how it is advertised (to the right audience), the way PR is handled by the author/publisher, how much exposure it gets, and a lot of other factors.
Of course, a bad novel probably won't get popular even if you get all of these right. But something doesn't need to be the best of the best to become the most popular.
For example, the most popular actor doesn't have to be the one with the best acting. He's the one who got the most suitable role in the most successful film. Is his success unwarranted? No. Does that make him the best actor? Also no.